Embolization has been widely accepted for its efficacy in treating various diseases including tumors, vascular lesions, and hemorrhages. For a safe and effective treatment, the selection of an appropriate embolic material is important. Liquid embolic materials may include ethanol; a mixture of ethylene vinyl alcohol copolymer dissolved in dimethyl sulfoxide (DMSO) and opacified with tantalum powder (available under the trade designation Onyx, from Covidien, Mansfield, Mass.); detergents, such as morrhuate sodium, or sotradecol; and cyanoacrylate. Liquid embolic materials such as ethanol, Onyx, and detergents can easily pass through capillaries, causing distal embolization or untargeted embolization. Cyanoacrylate is a non-resorbable tissue glue, which requires careful assessment of the proper dilution and control of vascular penetration due to its strong adhesion to tissue.